1.2 Flashcards
What is Newton’s first law of motion?
when external forces are balanced, an object will remain at rest or continue moving at a constant speed in a straight line.
What is Newton’s second law of motion?
When external forces acting on an object are unbalanced, the object accelerates in the direction of the unblanced force. This is summarised by the equation: F = ma
What is Newton’s third law of motion?
Every action has an equal and opposite reaction. So when two objects interact, they apply forces to one-another that are of equal magnitude and are in the opposite direction from one another.
What is the definiton of a Newton?
One Newton is the size of the unbalanced (resultant) force which will cause an object of mass 1kg to accelerate at 1ms^-1.
Break down the equation F = ma
F = unbalanced force (N)
m = mass (kg)
a = acceleration (ms^-2)
What is weight?
the force acting on an object due to gravity
Break down the equation W = mg
W = weight (N)
m = mass (kg)
g = gravitational field strength (Nkg^-1)
Describe friction
the force that opposes motion. This occurs between solid surfaces, liquids and within the air, causing air resistance
Describe free-fall and terminal velocity
Free-fall is the motion of an object where only the forces of weight and friction are acting upon it.
Terminal velocity occurs when a maximum velocity is reached, where the force of air resistance is balanced with the force of weight. As these forces are balanced, there is no acceleration and so terminal velocity is reached.
What is the gravitational field strength on Earth?
9.8 Nkg^-1
What is tension?
the pushing/pulling force excreted by each end of an object
How do you calculate tension?
F = ma
How do you calculate the magnitude of the resultant vector?
a^2 = b^2 + c^2
Calculate the direction of the resultant vector
tanx = opposite/adjacent
How do you calculate the vertical component of the given vector?
Fv = Fsinx
How do you calculate the horizontal component of the given vector?
Fh = Fcosx
Name the 4 forces acting on the boat below as it travels through water
thrust, air resistance, upthurst and weight
Define the term resultant force
the sum of all forces acting upon an object
Ignoring friction, what forces are acting on a box on a slope?
Only the force due to gravity (weight)
How do the calculate the force down the slope?
F = mgsinx
How do you calculate the force down?
F = mgcosx
What is work done?
The transfer of energy that occurs when an object is moved over a distance by an external force.
Break down the equation Ew = Fd
Ew = work done (J)
F = force (N)
d = distance (m)
How can you calculate kinetic energy given mass and velocity?
Ek = 1/2mv^2
Ek = kinetic energy (J)
m = mass (kg)
v = velocity (ms^-1)
How can you calculate gravitational potential energy given mass and height?
Ep = mgh
Ep = potential energy (J)
m = mass (kg)
g = gravitational field strength (Nkg^-1)
h = height (m)
What is power?
The rate at which energy is used
Break down the equation E = Pt
E = energy (J)
P = Power (W)
t = time (s)
When in a lift does your weight feel heavier than normal?
accelerating upwards
decelerate downwards
When in a lift does your weight feel lighter than normal?
accelerating downwards
decelerating upwards
When in a lift does your weight feel normal?
a constant speed
no speed
stationary
at rest
How are vectors added?
tip-to-tail
